The present invention relates to a drive unit for controlling drives of machine tools or production machines. Drives of machine tools or production machines are typically controlled by drive units which are commercially available. Typically, a drive unit that controls the drive is associated with each drive of the machine, which can be, for example, a motor with a connected gear and a load. One drive unit can also control several drives or motors.
FIG. 1 shows a conventional drive unit 2 and a number of components that are typically connected to the drive unit 2. A master control 1 transmits via a connection 11 to the drive unit 2 certain desired parameter values that control a motor 7 of the drive of the machine, such as the motor 7. The control functions for the motor 7 are implemented in signal electronics 5 which is controlled by a microprocessor (not shown) executing software. The signal electronics 5 reads the desired parameter values from a master controller 1 and receives, for example, transducer signals (not shown) from the motor 7 and determines therefrom control signals for a power electronics 6, which are then transmitted to the power electronics 6 via a connection 10. The power electronics 6 is essentially composed of a converter or an inverter, which provides power to the motor 7 and controls the motor. The drive unit 2 also includes an electronic power supply 3 that supplies power to the signal electronics, and a high power supply 4 that supplies power to the power electronics 6. The high power supply 4 derives its power from a power mains 8. The high power supply 4 also supplies power to the electronic power supply 3 via connection 16. The electronic power supply 3 supplies electric power to the signal electronics 5, whereas the high power supply 4 supplies electric power to the power electronic 6, as indicated by corresponding connections 17 and 19, respectively.
The drive unit 2, in particular the signal electronics 5, can be parameterized or initialized by a startup/diagnostic unit 9, and a diagnostic test can be performed when the drive unit malfunctions. The startup/diagnostic unit 9 is connected with the signal electronics 5 via a startup/diagnostic interface 20, which consists exclusively of data lines 12, for data exchange.
FIG. 2 shows another embodiment of a conventional drive unit 2. Identical elements or elements performing an identical function are designated with the same reference characters as the elements in FIG. 1. The embodiment of FIG. 2 is identical to the embodiment of FIG. 1, except that the electronic power supply 3 has here a dedicated separate connection to the power mains 8 controlled by a dedicated switch 15. The electronic power supply 3 is therefore supplied with electric power from a separate power feed, i.e. the power mains 8, which disadvantageously requires an additional interface for the drive unit 2 in FIG. 2.
Accordingly, the commonly used conventional drive units derive their electric power for the electronics either directly from the high power supply 4 (as shown in the prior art drive unit 2 of FIG. 1) or from a separately switchable power feed controlled by switch 15 (as shown in the prior art drive unit 2 of FIG. 2). In the first case, depicted in FIG. 1, the drive unit 2 can communicate with the startup/diagnostic unit 9 only when the high power supply 4 is electrically connected with the power mains 8. In the second case, depicted in FIG. 2, the drive unit 2 can communicate with the startup/diagnostic unit 9 also when the high power supply 4 is switched off, i.e. disconnected from the power mains 8. However, a second connection to the power mains 8 is then required, which may make particularly low-power devices too expensive. In addition, with both conventional embodiments, a power mains 8 must be available.
It would therefore be desirable and advantageous to provide an improved system for supplying electric energy to the signal electronics of a drive unit via a suitable startup/diagnostic interface in a simple and cost-effective manner, which obviates prior art shortcomings and is able to specifically supply electric power without requiring a connection to a power line.